adjust log verbosity to debug when no file-routes.json found

Fixes #2281

Author: taefi

packages/java/endpoint/src/main/java/com/vaadin/hilla/route/RouteUnifyingIndexHtmlRequestListener.java

@@ -119,7 +119,7 @@ private void loadLatestDevModeFileRoutesJsonIfNeeded() {
                 .getFrontendFolder().toPath().resolve("generated")
                 .resolve("file-routes.json").toFile();
         if (!devModeFileRoutesJsonFile.exists()) {
-            LOGGER.warn("Failed to find file-routes.json under {}",
+            LOGGER.debug("No file-routes.json found under {}",
                     deploymentConfiguration.getFrontendFolder().toPath()
                             .resolve("generated"));
             return;